Preparation of organohalosilanes

ABSTRACT

In an industrial process for preparing organohalosilanes by reacting metallic silicon particles with an organohalide in the presence of a copper catalyst, a contact mass composed of the metallic silicon and the catalyst further contains an effective amount of a phosphine chalcogenide compound. The invention drastically increases the silane formation rate and the utilization of silicon without lowering the selectivity of useful silane.

This invention relates to an industrial process for preparingorganohalosilanes.

BACKGROUND OF THE INVENTION

With respect to the synthesis of alkylhalosilanes, Rochow firstdisclosed in U.S. Pat. No. 2,380,995 direct synthesis reaction betweenmetallic silicon and alkyl halide in the presence of a copper catalyst.Since then, there have been reported a number of research works relatingto various co-catalysts used together with copper catalysts, reactors,additives used during reaction, and the like. In the industrialsynthesis of organohalosilanes, the selectivity of diorganodihalosilanewhich is most widely used in silicone resins, the formation rate ofsilanes, and the percent conversion of metallic silicon into usefulsilane are crucial. The selectivity of diorganodihalosilane is evaluatedin terms of a weight or molar ratio of dialkyldihalosilane to thesilanes produced and a T/D ratio.

Organohalosilane products contain diorganodihalosilane (D),triorganohalosilane (M), organotrihalosilane (T), etc. as well as otherby-products such as organohydrodihalosilane (H) and organohalodisilane.In particular, disilanes are known as a high-boiling fraction amongsilicone manufacturers using direct method organohalosilanes because fewprocesses are available for the effective utilization of disilanes, andmost disilanes are discarded. The T/D ratio is a compositional ratio oforganotrihalosilane to diorganodihalosilane in the entireorganohalosilanes produced, with a lower T/D ratio being preferred. Theformation rate of organohalosilane is represented by a space time yield(STY) which is the weight of crude organohalosilane produced per unittime relative to the weight of metallic silicon held in the reactor. Inorder to improve the content of diorganohalosilane produced, reduce theT/D ratio or increase the STY, various research works have been madewith a focus on the catalyst and co-catalyst.

USSR Application Specification No. 617,569 (Certificate of inventorshipNo. 122,749) dated Jan. 24, 1959 discloses reaction in the presence ofmetallic silicon-copper alloy with 20 to 40 ppm of antimony added.Allegedly, the dimethyldichlorosilane content is improved from 40% to60%. U.S. Pat. No. 4,500,724 discloses use of a copper/zinc/tin catalystcontaining 200 to 3,000 ppm of tin, thereby achieving an improvement ofT/D to 0.037. Japanese Patent Publication (JP-B) No. 6-92421 disclosesreaction using copper arsenide having an arsenic concentration of atleast 50 ppm. It is described in these patent references thatreactivity, more specifically the rate of reaction of metallic siliconis improved by adding these tin, antimony and arsenic co-catalysts to areaction contact mass comprising metallic silicon and copper.

USSR Application Specification No. 903,369 (Certificate of inventorshipNo. 178,817) dated Jun. 2, 1964 discloses that a co-catalyst selectedfrom the group consisting of zinc, bismuth, phosphorus (200 ppm),arsenic, tin, and iron improves the dimethyldichlorosilane content to72.1% from the value of 40-60% achieved by the above-referredApplication Specification No. 617,569 (Certificate of inventorship No.122,749). Also USSR Application Specification No. 1,152,943 (Certificateof inventorship No. 237,892) dated Nov. 20, 1969 discloses to add aphosphorus-copper-silicon alloy to a contact mass so as to give 2,500 to30,000 ppm of phosphorus, thereby improving the dimethyldichlorosilanecontent to 82.3%. Moreover, U.S. Pat. No. 4,602,101 corresponding toJP-B 5-51596 discloses that 25 to 2,500 ppm of a phosphorus compoundcapable of generating elemental phosphorus in the reactor is added to acontact mass. Although the results of reaction according to this U.S.patent are improved over the last-mentioned USSR patent, there stillremain many problems including hazard imposed by spontaneously ignitingelemental phosphorus and increased cost of raw materials. Then this USpatent is also unsuitable to apply to commercial scale reactors. Also,F. Komitsky et al., Silicon for the Chemical Industry IV, Geiranger,Norway (1998), page 217, proposes the addition of phosphorus in the formof copper phosphide, leaving problems including a low percentconversion, ineffective utilization of phosphorus, and difficult controlof a phosphorus concentration. U.S. Pat. No. 6,025,513 intends to addboron to a contact mass wherein the boron concentration is controlled soas to improve productivity. U.S. Pat. No. 5,059,706 discloses tointroduce a phosphorus compound in a vapor phase into a reactor forincreasing selectivity. U.S. Pat. No. 6,005,130 discloses to introduceorganomonophosphine for increasing selectivity.

However, the phosphorus base additives used in the prior art have anoutstanding trade-off between activity and composition selectivity. Inparticular, it is pointed out that oxide originating from phosphorus canexacerbate flow on the particle surface. Therefore, the conventionalphosphorus base additives offer few merits on the continuous operationof commercial scale reactors. Other additives are known from L. Rosch,W. Kalchauer et al., Silicon for the Chemical Industry IV, Sandefjord,Norway (1996) wherein monomethyldichlorosilane is introduced forimproving activity. This additive is effective only at the initialperiod, but not regarded as exerting a lasting effect during thecontinuous operation of commercial scale reactors.

Also, since the gas phase low-molecular weight compounds used in theprior art have a low evaporation temperature and lack thermal stability,it is difficult to precisely control the reaction at elevatedtemperatures. Under such circumstances, Ueno et al. proposed from adifferent point of view which had never been taken in the prior art, anindustrial process using organophosphino compounds as the activatingagent (see U.S. Pat. No. 6,215,012 and 6,242,629).

SUMMARY OF THE INVENTION

An object of the invention is to provide a novel and improved processfor preparing organohalosilanes at a drastically increased formationrate without lowering the selectivity of useful silane, therebyincreasing the utilization of silicon.

The present invention provides a process for preparing organohalosilanesby reacting metallic silicon particles with an organohalide in thepresence of a copper catalyst. The organohalosilanes have the generalformula (I):R¹ _(n)(H)_(m)SiX_((4−n−m))  (I)wherein R¹ is a monovalent hydrocarbon group, X is a halogen atom, n isan integer of 1 to 3, m is an integer of 0 to 2, and the sum of n+m isan integer of 1 to 3. A contact mass composed of the metallic siliconand the catalyst further contains an effective amount of a phosphinechalcogenide compound having in a molecule at least one group of thegeneral formula (II):

wherein R² and R³ are each independently a monovalent hydrocarbon groupor halogen atom, and Y is a chalcogen atom.

In summary, in the synthesis of organohalosilanes by reaction ofmetallic silicon with organohalide, the present invention incorporatesan effective amount of a specific phosphine chalcogenide compound in thecontact mass for the purpose of increasing the formation rate of usefulsilane. More particularly, conventional additives which are knowneffective to improve the useful silane content are phosphorus compoundsincluding metallic phosphorus, phosphorus oxide, copper phosphide, tinphosphide, zinc phosphide, aluminum phosphide, antimony phosphide,phosphorus trichloride, trimethylphosphine, and triphenylphosphine. Weaddressed the actual drawback of the direct method or Rochow methodusing such phosphorus compounds as a co-catalyst, that is, the problemthat the phosphorus compounds serve to increase the diorganodihalosilanecontent, but reduce the reaction rate and hence, the productivity ofuseful silane. We also intended to realize in a commercial plant anincrease of production rate which has never been accomplished when thedirect method is carried out using as an activator conventionaladditives known to improve activity or such compounds asmethyldichlorosilane. In such efforts, we have found that the aboveobjects are attained by adding phosphine chalcogenide compounds, whichare less expensive and economically more advantageous than theorganophosphine compounds, to the contact mass.

The process of the invention is by adding a catalytic amount of aspecific phosphine chalcogenide compound to a contact mass which becomeseffective, independent of the form of copper catalyst, for increasingthe reaction rate of Rochow reaction, without catalyzing side reactionand without decreasing the yield of the main component,diorganodihalosilane. The production rate of useful silane is thusimproved while the catalysis of the phosphine chalcogenide compoundlasts long. In this sense, the present invention is completely differentfrom the prior art improvements which are formulations relying on theshort-lived effects of catalysts.

The inventors assumed that a phosphine chalcogenide compound, when addedin a very small amount, attacks the primary catalyst, copper whereby theequilibrium of oxidation-reduction state on its surface is shifted tocreate copper halide which is necessary to induce Rochow reaction activesite-forming reaction, while the phosphine chalcogenide compound itselfconverts to a phosphine compound which does not catalyze side reaction.Based on this assumption, we made a study on a series of phosphinechalcogenide compound. We have discovered that in the synthesis oforganohalosilanes by reaction of metallic silicon with organohalide, acontact mass containing an effective amount of the above-specifiedphosphine chalcogenide compound is effective for increasing theproduction rate for thereby increasing the utilization of siliconwithout reducing the proportion of useful silane. That is, the presentinvention is predicated on the discovery that a contact mass containinga very small, but effective amount of the phosphine chalcogenidecompound can significantly increase the production rate withoutsubstantially changing the useful silane content.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The process for preparing organohalosilanes according to the inventioninvolves the step of reacting metallic silicon particles with anorganohalide in the presence of a copper catalyst to thereby formorganohalosilanes of the following general formula (I):R¹ _(n)(H)_(m)SiX_((4−n−m))  (I)wherein R¹ is a monovalent hydrocarbon group, X is a halogen atom, n isan integer of 1 to 3, m is an integer of 0 to 2, and n+m is an integerof 1 to 3.

In formula (I), suitable monovalent hydrocarbon groups represented by R¹include C₁₋₆ alkyl, alkenyl and aryl groups, preferably alkyls such asmethyl, ethyl and propyl and phenyl, with methyl being most preferred.It is preferred that n is 2, m is 0 and n+m=2. X is typically chlorine,bromine or fluorine, with chlorine being preferred.

The metallic silicon used herein preferably has a silicon purity of atleast 97% by weight, especially at least 98% by weight. Prior to use,the metallic silicon is preferably ground into particles with anappropriate particle size. Where the reactor used is a fluidized bed orstirred bed reactor, the metallic silicon powder should preferably havea particle size in the range of 5 to 150 μm, corresponding to 50% of theweight base cumulative size distribution curve on sieving, in order thatthe metallic silicon powder have good fluidity.

The organohalides to be reacted with metallic silicon to formorganohalosilanes are preferably those of 1 to 6 carbon atoms includingmethyl chloride, ethyl chloride, propyl chloride, methyl bromide, ethylbromide, benzene chloride and benzene bromide. Of these, methyl chlorideand benzene chloride are preferable in the industry. Methyl chloride ismost useful because organohalosilanes, typically dimethyldichlorosilane,produced therefrom find a wide variety of applications as the rawmaterial for many silicone resins.

The copper catalyst used herein may be selected from various forms ofcopper including elemental copper (or metallic copper) such as powderedcopper and stamped copper, and copper compounds such as cuprous oxide,cupric oxide, and copper halides. Any of promoters such as zinc, tin,antimony, aluminum, phosphorus and arsenic may be used as theco-catalyst. The co-catalyst may be used alone or in the form of analloy with copper. Examples of the co-catalyst include metallic zinc,zinc compounds such as zinc-copper alloys, zinc chloride, zinc oxide,and zinc acetate, metallic tin, tin compounds such as tin-copper alloys,tin chloride and tin oxide, metallic antimony, antimony compounds suchas antimony chloride and antimony oxide, metallic aluminum, aluminumcompounds such as aluminum chloride and aluminum oxide, metallicphosphorus, inorganic phosphorus compounds such as phosphorustrichloride and phosphorus oxide, and organic phosphorus compounds, forexample, monoalkylphosphines such as trimethylphosphine andtriphenylphosphine. Suitable combinations of the copper catalyst withthe co-catalyst are copper alloys including Cu—Zn, Cu—Sn, and Cu—Zn—Sn(or Sb or As) as mentioned above. Of the above-mentioned co-catalysts,metallic zinc, zinc compounds, metallic tin, tin compounds, metallicantimony, antimony compounds, metallic aluminum, aluminum compounds,metallic phosphorus, and phosphorus compounds (excluding phosphoniumcompounds) are preferred.

The copper catalyst may be admitted alone into the reactor. The coppercatalyst is used in an effective amount. An appropriate amount of thecopper catalyst charged is about 0.1 to 10 parts, and more preferablyabout 2 to 8 parts by weight, calculated as copper, per 100 parts byweight of the metallic silicon powder. The co-catalyst is also used inan effective amount, preferably 0.0001 to 3 parts, especially 0.001 to 1part by weight per 100 parts by weight of the metallic silicon powder.Specifically, zinc is used in an amount of 0.01 to 2 parts, especially0.05 to 1 part by weight; tin, antimony or arsenic, alone or incombination, is used in an amount of 0.001 to 0.05 part, especially0.005 to 0.01 part by weight; aluminum is used in an amount of 0.001 to1 part, especially 0.005 to 0.5 part by weight; and phosphorus is usedin an amount of 0.001 to 2 parts, especially 0.005 to 1 part by weight,each per 100 parts by weight of the metallic silicon powder. In the caseof compounds such as zinc compounds, they are preferably added so as toprovide the respective metals in the above-described amounts. A mixtureof two or more co-catalysts may be used.

According to the invention, the contact mass composed of metallicsilicon particles, the copper catalyst and optionally, the co-catalystfurther contains an effective amount of a phosphine chalcogenidecompound having per molecule at least one group of the following generalformula (II):

wherein R² and R³ are each independently a monovalent hydrocarbon groupor halogen atom, and Y is a chalcogen atom.

Suitable monovalent hydrocarbon groups represented by R² and R³ includealkyl, aryl, aralkyl and alkenyl groups having 1 to 10 carbon atoms,preferably 1 to 8 carbon atoms, and specifically methyl, ethyl, propyl,phenyl, butyl, pentyl, hexyl, and benzyl. Examples of the halogen atomrepresented by R² and R³ include chlorine, bromine and fluorine, withchlorine being preferred. Examples of the chalcogen atom represented byY include oxygen, sulfur, selenium and tellurium, with oxygen and sulfurbeing preferred.

It is desirable for the contact mass to contain two or more phosphinechalcogenide compounds having per molecule at least one group of formula(II).

Of the phosphine chalcogenide compounds, those having the followinggeneral formula (III) or (IV) are preferred.

In formula (III), R⁴, R⁵ and R⁶ are each independently a monovalenthydrocarbon group or halogen atom, and Y is as defined above.

In formula (IV), R⁷, R⁸, R⁹ and R¹⁰ are each independently a monovalenthydrocarbon group or halogen atom, Z is a divalent hydrocarbon group, αis an integer of at least 0, and β is an integer of at least 1.

Illustratively, R⁴ to R¹⁰ which may be the same or different aremonovalent hydrocarbon groups having 1 to 10 carbon atoms, preferably 1to 8 carbon atoms, as exemplified above for R² and R³. Among others,methyl, ethyl, propyl, butyl, pentyl, hexyl, phenyl and benzyl arepreferred.

Examples of the divalent hydrocarbon group represented by Z includealkylene, alkenylene and cycloalkylene groups having 1 to 20 carbonatoms, preferably 1 to 10 carbon atoms. Among others, methylene,ethylene, propylene, butylene, pentylene and decylene are preferred.

The subscript α is an integer inclusive of 0, preferably 0 or 1, and βis an integer of at least 1, preferably 1 to 5.

Preferred examples of the phosphine chalcogenide include

-   -   tri-n-octylphosphine oxide, triphenylphosphine oxide,    -   octyl(phenyl)-N,N′-diisobutylcarbamoylmethylphosphine oxide,    -   diphenylphosphinylhydroquinone, triphenylphosphine sulfide,    -   bis(dichlorophosphoryl)methane,    -   1,2-bis(diethylphosphino)ethane oxide,    -   bis(dimethylamino)phosphoryl chloride,    -   bis(dimethylamino)thiophosphoryl chloride,    -   3-bis(dimethylphosphino)propane oxide,    -   cis-1,2-bis(diphenylphosphino)ethylene dioxide,    -   tetraethylethylene diphosphonate, tetraethylmethylene    -   diphosphonate, tetraethylpropylene diphosphonate,    -   tetramethylphosphine disulfide, tetramethylmethylene    -   diphosphonate, tetraphenyldiphosphine disulfide,    -   tetra-I-propylmethylene diphosphonate,    -   tetra-n-propylmethylene diphosphonate,    -   tetra-I-propylpropylene diphosphonate, triallylphosphine    -   oxide, tri-n-amyl phosphate, tribenzylphosphine oxide,    -   tri-n-butylphosphine oxide, tri-n-butylphosphine sulfide,    -   tri-t-butylphosphine sulfide, tricyclohexylphosphine oxide,    -   tricyclohexylphosphine sulfide, tricyclohexylphosphide,    -   triethylphosphine oxide, triethylphosphine sulfide,    -   trimethylphosphine oxide, trimethylphosphine sulfide,    -   trimethyl phosphorothionate, triphenylphosphine sulfide,    -   triphenyl phosphoranyl-2-propanone, tri-n-propylphosphine    -   oxide, tris(2-chloroethyl)phosphate,    -   tris(p-dimethylaminophenyl)phosphine oxide,    -   tris(o-methoxyphenyl)phosphine oxide, and triphenyl selenide.

To improve the productivity of organohalosilane, an effective amount ofthe phosphine chalcogenide is used, the effective amount beingdetermined on the basis of the entire amount of silicon and depending onthe reaction time, scale and grade of metallic silicon. Preferably 0.1to 25,000 parts, and especially 1 to 5,000 parts by weight of thephosphine chalcogenide is used per million parts by weight of metallicsilicon powder.

In the contact mass, an anti-agglomerating agent such as silica,diatomaceous earth, mica, talc, alumina, titanium oxide and carbon maybe included in order to prevent the contact mass from agglomerating. Ifdesired, hydrogen, hydrogen chloride gas, hydrosilane or chlorosilanemay be fed in order to control the composition or activity of thecontact mass.

In carrying out the process for preparing organohalosilanes according tothe invention, any well-known method may be used except for the use ofthe phosphine chalcogenide. More specifically, when Rochow reaction iscarried out between an organohalide and a contact mass includingmetallic silicon, copper or copper compound and optionally, aco-catalyst such as Zn, Sn, Sb, Al, P or compound thereof at atemperature in the range of about 230 to 600° C., preferably about 250to 600° C., the phosphine chalcogenide is added to the contact masswhereby diorganohalosilanes of formula (I) are produced at asignificantly increased production rate or space time yield (STY).

The process of the invention can be carried out in any of fixed bedreactors, stirred bed reactors and fluidized bed reactors. From theindustrial aspect, a fluidized bed reactor suited for continuousoperation is employed.

The organohalide is previously heated and gasified before it is fed intothe reactor. The organohalide gas may be fed alone or along with aninert gas in a sufficient amount to fluidize the contact mass. Thefluidizing amount is determined as appropriate from the diameter of thereactor and the superficial velocity.

In the step of heating the contact mass or imparting catalytic activityto the contact mass, an inert gas is used for fluidizing the contactmass in the reactor. Such an inert gas may be nitrogen, helium or argongas, for example, with the nitrogen gas being preferable from theeconomic standpoint. The flow velocity of the inert gas fed in this andsubsequent steps is at least the incipient fluidization velocity of thecontact mass, and preferably about 5 times the incipient fluidizationvelocity. A flow velocity below the range of the inert gas may oftenfail to achieve uniform fluidization of the contact mass. If the flowvelocity of the inert gas is above the range, metallic silicon powdermay be excessively scattered with increased losses of the inert gas andheat. It is recommended to recycle the inert gas and the organohalide.

After the contact mass is given catalytic activity as mentioned above,the organohalide is introduced into the reactor where gas-solidcatalytic reaction takes place between the organohalide and metallicsilicon to form organohalosilanes.

EXAMPLE

Examples of the invention are given below by way of illustration and notby way of limitation. Parts are by weight.

Comparative Example 1

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powderand 4 parts of a catalyst in the form of metallic copper powder. Then agas mixture of methyl chloride and nitrogen was introduced into thereactor at a rate of 14.4 Nl/min and the reactor was heated at atemperature of 310° C. whereupon reaction continued. A mixture ofmetallic silicon powder and the catalyst was fed from the reactor bottomso as to keep constant the amount of the contact mass in the reactor.Reaction was continued for 6 hours, following which the reaction wasterminated. The run was repeated 6 times. Reported in Table 1 are theconcentrations of impurities in the metallic silicon used, an average ofsilane formation rate from the start to the end of reaction, and anaverage of cumulative content of useful silane.

Comparative Example 2

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powderand 5 parts of a catalyst in the form of copper oxide powder. Then a gasmixture of methyl chloride and nitrogen was introduced into the reactorat a rate of 14.4 Nl/min and the reactor was heated at a temperature of320° C. whereupon reaction continued. A mixture of metallic siliconpowder and the catalyst was fed from the reactor bottom so as to keepconstant the amount of the contact mass in the reactor. Reaction wascontinued for 6 hours, following which the reaction was terminated. Therun was repeated 2 times. Reported in Table 1 are the concentrations ofimpurities in the metallic silicon used, an average of silane formationrate from the start to the end of reaction, and an average of cumulativecontent of useful silane.

Example 1

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,4 parts of a catalyst in the form of metallic copper powder, and 0.12part of triphenylphosphine oxide [(C₆H₅)₃P═O]. Then a gas mixture ofmethyl chloride and nitrogen was introduced into the reactor at a rateof 14.4 Nl/min and the reactor was heated at a temperature of 310° C.whereupon reaction continued. A mixture of metallic silicon powder andthe catalyst was fed from the reactor bottom so as to keep constant theamount of the contact mass in the reactor. Reaction was continued for 6hours, following which the reaction was terminated. The run was repeated2 times. Reported in Table 1 are the concentrations of impurities in themetallic silicon used, an average of silane formation rate from thestart to the end of reaction, and an average of cumulative content ofuseful silane.

Example 2

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,5 parts of a catalyst in the form of copper oxide powder, and 0.12 partof triphenylphosphine oxide [(C₆H₅)₃P═O]. Then a gas mixture of methylchloride and nitrogen was introduced into the reactor at a rate of 14.4Nl/min and the reactor was heated at a temperature of 320° C. whereuponreaction continued. A mixture of metallic silicon powder and thecatalyst was fed from the reactor bottom so as to keep constant theamount of the contact mass in the reactor. Reaction was continued for 6hours, following which the reaction was terminated. The run was repeated2 times. Reported in Table 1 are the concentrations of impurities in themetallic silicon used, an average of silane formation rate from thestart to the end of reaction, and an average of cumulative content ofuseful silane.

Example 3

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,4 parts of a catalyst in the form of metallic copper powder, and 0.04part of triphenylphosphine oxide [(C₆H₅)₃P═O]. Then a gas mixture ofmethyl chloride and nitrogen was introduced into the reactor at a rateof 14.4 Nl/min and the reactor was heated at a temperature of 310° C.whereupon reaction continued. A mixture of metallic silicon powder andthe catalyst was fed from the reactor bottom so as to keep constant theamount of the contact mass in the reactor. Reaction was continued for 10hours, following which the reaction was terminated. The run was repeated2 times. Reported in Table 1 are the concentrations of impurities in themetallic silicon used, an average of silane formation rate from thestart to the end of reaction, and an average of cumulative content ofuseful silane.

Example 4

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,5 parts of a catalyst in the form of copper oxide powder, and 0.04 partof triphenylphosphine oxide [(C₆H₅)₃P═O]. Then a gas mixture of methylchloride and nitrogen was introduced into the reactor at a rate of 14.4Nl/min and the reactor was heated at a temperature of 320° C. whereuponreaction continued. A mixture of metallic silicon powder and thecatalyst was fed from the reactor bottom so as to keep constant theamount of the contact mass in the reactor. Reaction was continued for 10hours, following which the reaction was terminated. The run was repeated2 times. Reported in Table 1 are the concentrations of impurities in themetallic silicon used, an average of silane formation rate from thestart to the end of reaction, and an average of cumulative content ofuseful silane.

Example 5

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,4 parts of a catalyst in the form of metallic copper powder, and 0.2part of cis-1,2-bis(diphenylphosphino)ethylene dioxide[((C₆H₅)₂P═O)₂—C₂H₄]. Then a gas mixture of methyl chloride and nitrogenwas introduced into the reactor at a rate of 14.4 Nl/min and the reactorwas heated at a temperature of 310° C. whereupon reaction continued. Amixture of metallic silicon powder and the catalyst was fed from thereactor bottom so as to keep constant the amount of the contact mass inthe reactor. Reaction was continued for 6 hours, following which thereaction was terminated. The run was repeated 2 times. Reported in Table1 are the concentrations of impurities in the metallic silicon used, anaverage of silane formation rate from the start to the end of reaction,and an average of cumulative content of useful silane.

Example 6

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,5 parts of a catalyst in the form of copper oxide powder, and 0.2 partof cis-1,2-bis(diphenylphosphino)ethylene dioxide [((C₆H₅)₂P═O)₂—C₂H₄].Then a gas mixture of methyl chloride and nitrogen was introduced intothe reactor at a rate of 14.4 Nl/min and the reactor was heated at atemperature of 320° C. whereupon reaction continued. A mixture ofmetallic silicon powder and the catalyst was fed from the reactor bottomso as to keep constant the amount of the contact mass in the reactor.Reaction was continued for 6 hours, following which the reaction wasterminated. The run was repeated 2 times. Reported in Table 1 are theconcentrations of impurities in the metallic silicon used, an average ofsilane formation rate from the start to the end of reaction, and anaverage of cumulative content of useful silane.

Example 7

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,4 parts of a catalyst in the form of metallic copper powder, and 0.05part of cis-1,2-bis(diphenylphosphino)ethylene dioxide[((C₆H₅)₂P═O)₂—C₂H₄]. Then a gas mixture of methyl chloride and nitrogenwas introduced into the reactor at a rate of 14.4 Nl/min and the reactorwas heated at a temperature of 310° C. whereupon reaction continued. Amixture of metallic silicon powder and the catalyst was fed from thereactor bottom so as to keep constant the amount of the contact mass inthe reactor. Reaction was continued for 10 hours, following which thereaction was terminated. The run was repeated 2 times. Reported in Table1 are the concentrations of impurities in the metallic silicon used, anaverage of silane formation rate from the start to the end of reaction,and an average of cumulative content of useful silane.

Example 8

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,5 parts of a catalyst in the form of copper oxide powder, and 0.05 partof cis-1,2-bis(diphenylphosphino)ethylene dioxide [((C₆H₅)₂P═O)₂—C₂H₄].Then a gas mixture of methyl chloride and nitrogen was introduced intothe reactor at a rate of 14.4 Nl/min and the reactor was heated at atemperature of 320° C. whereupon reaction continued. A mixture ofmetallic silicon powder and the catalyst was fed from the reactor bottomso as to keep constant the amount of the contact mass in the reactor.Reaction was continued for 10 hours, following which the reaction wasterminated. The run was repeated 2 times. Reported in Table 1 are theconcentrations of impurities in the metallic silicon used, an average ofsilane formation rate-from the start to the end of reaction, and anaverage of cumulative content of useful silane.

Example 9

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,4 parts of a catalyst in the form of metallic copper powder, and 0.15part of tribenzylphosphine oxide [(C₆H₅CH₂)₃P═O]. Then a gas mixture ofmethyl chloride and nitrogen was introduced into the reactor at a rateof 14.4 Nl/min and the reactor was heated at a temperature of 310° C.whereupon reaction continued. A mixture of metallic silicon powder andthe catalyst was fed from the reactor bottom so as to keep constant theamount of the contact mass in the reactor. Reaction was continued for 6hours, following which the reaction was terminated. The run was repeated2 times. Reported in Table 1 are the concentrations of impurities in themetallic silicon used, an average of silane formation rate from thestart to the end of reaction, and an average of cumulative content ofuseful silane.

Example 10

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,5 parts of a catalyst in the form of copper oxide powder, and 0.15 partof tribenzylphosphine oxide [(C₆H₅CH₂)₃P═O]. Then a gas mixture ofmethyl chloride and nitrogen was introduced into the reactor at a rateof 14.4 Nl/min and the reactor was heated at a temperature of 320° C.whereupon reaction continued. A mixture of metallic silicon powder andthe catalyst was fed from the reactor bottom so as to keep constant theamount of the contact mass in the reactor. Reaction was continued for 6hours, following which the reaction was terminated. The run was repeated2 times. Reported in Table 1 are the concentrations of impurities in themetallic silicon used, an average of silane formation rate from thestart to the end of reaction, and an average of cumulative content ofuseful silane.

Example 11

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,4 parts of a catalyst in the form of metallic copper powder, and 0.12part of tri-n-propylphosphine oxide [(n—C₃H₇)₃P═O]. Then a gas mixtureof methyl chloride and nitrogen was introduced into the reactor at arate of 14.4 Nl/min and the reactor was heated at a temperature of 310°C. whereupon reaction continued. A mixture of metallic silicon powderand the catalyst was fed from the reactor bottom so as to keep constantthe amount of the contact mass in the reactor. Reaction was continuedfor 10 hours, following which the reaction was terminated. The run wasrepeated 2 times. Reported in Table 1 are the concentrations ofimpurities in the metallic silicon used, an average of silane formationrate from the start to the end of reaction, and an average of cumulativecontent of useful silane.

Example 12

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,5 parts of a catalyst in the form of copper oxide powder, and 0.12 partof tri-n-propylphosphine oxide [(n—C₃H₇)₃P═O]. Then a gas mixture ofmethyl chloride and nitrogen was introduced into the reactor at a rateof 14.4 Nl/min and the reactor was heated at a temperature of 320° C.whereupon reaction continued. A mixture of metallic silicon powder andthe catalyst was fed from the reactor bottom so as to keep constant theamount of the contact mass in the reactor. Reaction was continued for 10hours, following which the reaction was terminated. The run was repeated2 times. Reported in Table 1 are the concentrations of impurities in themetallic silicon used, an average of silane formation rate from thestart to the end of reaction, and an average of cumulative content ofuseful silane.

Comparative Example 3

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powder,4 parts of a catalyst in the form of metallic copper powder, and 0.2part of copper phosphide. Then a gas mixture of methyl chloride andnitrogen was introduced into the reactor at a rate of 14.4 Nl/min andthe reactor was heated at a temperature of 310° C. whereupon reactioncontinued. After 6 hours, the reaction was terminated. The run wasrepeated 3 times. Reported in Table 1 are the concentrations ofimpurities in the metallic silicon used, an average of silane formationrate from the start to the end of reaction, and an average of cumulativecontent of useful silane.

Comparative Example 4

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powderand 4 parts of a catalyst in the form of metallic copper powder. Then agas mixture of methyl chloride and nitrogen was introduced into thereactor at a rate of 14.4 Nl/min. Nitrogen gas was bubbled into a 0.1 Mtoluene solution of phosphorus trichloride to produce phosphorustrichloride vapor, which was introduced into the reactor along with thenitrogen carrier. The reactor was heated at a temperature of 310° C.whereupon reaction continued. After 6 hours, the reaction wasterminated. The run was repeated 3 times. Reported in Table 1 are theconcentrations of impurities in the metallic silicon used, an average ofsilane formation rate from the start to the end of reaction, and anaverage of cumulative content of useful silane.

Comparative Example 5

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powderand 4 parts of a catalyst in the form of metallic copper powder. Then agas mixture of methyl chloride and nitrogen was introduced into thereactor at a rate of 14.4 Nl/min. Nitrogen gas was bubbled into a 0.1 Mtoluene solution of trimethylphosphine to produce trimethylphosphinevapor, which was introduced into the reactor along with the nitrogencarrier. The reactor was heated at a temperature of 310° C. whereuponreaction continued. After 6 hours, the reaction was terminated. The runwas repeated 3 times. Reported in Table 1 are the concentrations ofimpurities in the metallic silicon used, an average of silane formationrate from the start to the end of reaction, and an average of cumulativecontent of useful silane.

Comparative Example 6

A fluidized bed reactor of carbon steel having a diameter of 75 mm and aheight of 900 mm was charged with 100 parts of metallic silicon powderand 4 parts of a catalyst in the form of metallic copper powder. Then agas mixture of methyl chloride and nitrogen was introduced into thereactor at a rate of 14.4 Nl/min. Nitrogen gas was bubbled into a 0.1Mtoluene solution of monomethyldichlorosilane to producemonomethyldichlorosilane vapor, which was introduced into the reactoralong with the nitrogen carrier. The reactor was heated at a temperatureof 310° C. whereupon reaction continued. After 6 hours, the reaction wasterminated. The run was repeated 3 times. Reported in Table 1 are theconcentrations of impurities in the metallic silicon used, an average ofsilane formation rate from the start to the end of reaction, and anaverage of cumulative content of useful silane.

TABLE 1 Additive Useful Reaction concen- Formation silane temperature FeAl Ca tration¹⁾ rate²⁾ content³⁾ Example (° C.) (%) (%) (%) Additive(%/Si) (g/h) (%) Comparative 310 0.26 0.13 0.07 none — 276 87.7 Example1 Comparative 320 0.28 0.14 0.06 none — 259 85.9 Example 2 Example 1 3100.25 0.15 0.04 triphenylphosphine oxide 0.12 435 90.1 Example 2 320 0.240.19 0.06 triphenylphosphine oxide 0.12 391 88.1 Example 3 310 0.25 0.150.04 triphenyiphosphine oxide 0.04 445 89.8 Example 4 320 0.24 0.19 0.06triphenyiphosphine oxide 0.04 425 87.7 Example 5 310 0.28 0.13 0.06cis-1,2- 0.20 669 91.3 bis(diphenylphosphino) ethylene dioxide Example 6320 0.29 0.19 0.06 cis-1,2- 0.20 532 89.0 bis(diphenylphosphino)ethylene dioxide Example 7 310 0.28 0.13 0.06 cis-1,2- 0.05 616 90.0bis(diphenylphosphino) ethylene dioxide Example 8 320 0.29 0.19 0.06cis-1,2- 0.05 519 89.2 bis(diphenylphosphino) ethylene dioxide Example 9310 0.27 0.11 0.08 tribenzylphosphine oxide 0.15 556 89.8 Example 10 3200.27 0.18 0.07 tribenzylphosphine oxide 0.15 525 88.4 Example 11 3100.24 0.15 0.05 tri-n-propylphosphine 0.12 555 89.2 oxide Example 12 3200.25 0.19 0.06 tri-n-propylphosphine 0.12 550 88.2 oxide Comparative 3100.26 0.13 0.07 copper phosphide 0.20 276 89.8 Example 3 Comparative 3100.26 0.13 0.07 phosphorus trichloride ⁴⁾ 161 88.0 Example 4 Comparative310 0.28 0.12 0.06 trimethylphosphine ⁴⁾ 138 89.6 Example 5 Comparative310 0.26 0.13 0.07 Monomethyldichlorosilane ⁴⁾ 288 87.7 Example 6 Note:¹⁾The concentration (wt %) of additive based on the weight of silicon.^(2),) ³⁾an average of 6 runs for Comparative Example 1, an average of 2runs for Examples 1-12 and Comparative Example 2, and an average of 3runs for Comparative Examples 3-6. ⁴⁾In Comparative Examples 4-6, theadditive was introduced into the reactor along with methyl chloride bybubbling nitrogen gas into a 0.1M toluene solution of the additive forcarrying its vapor with nitrogen gas.

There has been described an industrial process for preparingorganohalosilanes using a contact mass containing an effective amount ofa phosphine chalcogenide, thereby drastically increasing the formationrate and the utilization of silicon without lowering the selectivity ofuseful silane.

Japanese Patent Application No. 2002-120393 is incorporated herein byreference.

Reasonable modifications and variations are possible from the foregoingdisclosure without departing from either the spirit or scope of thepresent invention as defined by the claims.

1. A process for preparing organohalosilanes having the general formula(I):R¹ _(n)(H)_(m)SiX_((4−n−m))  (I) wherein R¹ is a monovalent hydrocarbongroup, X is a halogen atom, n is an integer of 1 to 3, m is an integerof 0 to 2, and the sum of n+m is an integer of 1 to 3, by reactingmetallic silicon particles with an organohalide in the presence of acopper catalyst, wherein a contact mass composed of the metallic siliconand the catalyst further contains an effective amount of a phosphinechalcogenide compound having in a molecule at least one group of thegeneral formula (II):

wherein R² and R³ are each independently a monovalent hydrocarbon groupor halogen atom, and Y is a chalcogen atom.
 2. The process of claim 1wherein said phosphine chalcogenide compound has the general formula(III):

wherein R⁴, R⁵ and R⁶ are each independently a monovalent hydrocarbongroup or halogen atom, and Y is as defined above.
 3. The process ofclaim 1 wherein said phosphine chalcogenide compound has the generalformula (IV):

wherein R⁷, R⁸, R⁹ and R¹⁰ are each independently a monovalenthydrocarbon group or halogen atom, Z is a divalent hydrocarbon group, αis an integer of at least 0, and β is an integer of at least
 1. 4. Theprocess of claim 1 wherein the contact mass further contains at leastone co-catalyst selected from the group consisting of metallic zinc,zinc compounds, metallic tin, tin compounds, metallic antimony, antimonycompounds, metallic aluminum, aluminum compounds, metallic phosphorus,and phosphorus compounds (excluding phosphonium compounds).